1. Field of the Invention
This invention relates generally to methods and devices for surgically joining separate pieces of tissue to one another, and more particularly to surgically joining a tubular graft of tissue to a separate piece of tissue.
2. Related Art
In performing bypass surgery, it is a known practice to repair a clogged or an otherwise damaged segment of tubular tissue, for example a coronary artery, by attaching a healthy section of artery, for example, a mammary artery, to the tubular tissue below the clog or damaged segment so that blood flows from the healthy section of artery into the tubular tissue below the clogged or damaged segment. In addition, it is also known to bypass a clogged or damaged section of artery (e.g., a coronary artery) by forming a graft made of a section of vein harvested from elsewhere (e.g., a Saphenous vein harvested from the thigh) extending from the aorta to a section of the clogged or damaged artery beyond the clog or damage. The resulting graft is known as a Coronary Artery Bypass Graft (CABG—pronounced “cabbage”) and the procedure to form the graft is known as a CABG procedure.
While performing the procedures mentioned above, a surgeon ordinarily will perform a sternectomy, a procedure to open the patient's chest to provide access to the patients heart. Thereafter, the patient is typically put on a bypass system that performs the function of the patient's own heart and lungs as well as cools and warms the patient's blood. As the patient is put on the bypass system, the patient's heart is stopped or “arrested” so that the surgeon may perform the CABG procedure.
It is important that each end of the CABG graft is well attached to the aorta or coronary artery, respectively. This is necessary in order to provide a leak-proof anastomosis and also to allow the tissue to heal together into a strong, leak-proof connection. This connection is generally done by the surgeon making numerous stitches of suture (typically 6-8 on each end of the graft) between the vessel and the tissue that the graft is being joined to. In some cases, the surgeon must replace sutures that do not create a leak-proof anastomosis between the pieces of tissue. After the CABG procedure is complete, the patient is taken off the bypass system, the patient's heart allowed to restart and the patient's chest closed.
The entire procedure is ordinarily quite exhausting and requires a long time to complete the procedure, generally ranging between 2 to 6 hours or more. Statistically, 3-7% of patients that are put on a bypass system experience some form of neurological complications. The longer the patient is on the bypass system, the more likely he or she is to experience such complications. It typically takes a surgeon between 6-12 minutes to attach each end of the graft to the aorta and coronary artery, respectively. Much of the surgeon's time is spent making certain that the segments of tissue are joined together in a leak-proof anastomosis. Generally, this requires the surgeon to make numerous stitches of suture between the segments of tissue being joined to one another, and in some cases replacing sutures that do not create a leak-proof anastomosis between the pieces of tissue.
Though using sutures to join segments of tissue to one another in open heart surgery, or other forms of surgery, has proven successful, not only does it require a longer than desirable amount of time in surgery, there is also a danger of the suture becoming damaged. Damage to a portion of the suture may occur in many ways, such as through inadvertent grasping or clamping by a surgical instrument or through nicking a suture with the needle as an adjacent suture is installed. Ordinarily, a damaged piece of suture has a substantially reduced tensile strength and thus may ultimately fail to maintain the pieces of tissue joined to one another.